I would not call it a money grab for property taxes. Many of these parks are permanent residences and as such use tax dollars for public services, hospitals fire and rescue, police, water, sewer, power. Why should they be charged nothing for all those things?
There are places like Newfoundland that have similar laws regarding porches and many houses do not have porches and stairs because that would make them subject to taxes. Pretty low rent way to live if you ask me. Don't say bad things about welfare scammers if this is how you think it should be.